Bombings are mainly to blame for the deaths of 173 civilians in the last month, a 33% jump over the same period in 2009. The news is considered worrisome in light of an upcoming U.S. offensive.

Reporting from Kabul, Afghanistan — Civilian deaths in the last month jumped by one-third over the same period a year ago, the Afghan government said Sunday.

The surge in noncombatant fatalities is considered particularly worrisome in advance of a major Western military offensive in Kandahar province this spring and summer. Typically, intensified fighting between insurgents and foreign forces brings a corresponding increase in civilian casualties.

Afghanistan's Interior Ministry said 173 civilians were killed between March 21 and April 21 of this year, the most recent period for which figures were available. That represented a 33% increase from the same dates in 2009, ministry spokesman Zemari Bashary said during a news conference in Kabul, the capital.

Bashary said the deaths, coupled with the injuries of 380 civilians, were largely caused by explosions — either suicide bombings or roadside bombs. The latest example of that came Sunday, when officials in Paktia province, near the Pakistani border, reported that a civilian minibus had hit an improvised explosive device, or IED, wrecking it and killing or maiming most of those aboard.

Conflicting reports of the number of casualties could not immediately be resolved, but it appeared that at least half a dozen people had been killed and about twice as many hurt, with women and children among the victims.

IEDs are almost always planted by insurgents with the aim of striking military convoys, but civilians travel the same roads, and their rickety cars and buses — usually packed with passengers — are far more vulnerable to attack than the armored vehicles used by troops.

Civilian deaths have exacerbated tensions between the government of Afghan President Hamid Karzai and his Western backers. Karzai has repeatedly denounced noncombatant fatalities and urged greater care on the part of foreign troops, even though most such deaths are blamed on insurgents.

U.S. Army Gen. Stanley A. McChrystal, the commander of all Western troops in Afghanistan, has made safeguarding civilian lives a top priority. But military officials acknowledge that noncombatants are often caught in harm's way during upsurges in battlefield activity, such as the fighting this year in Helmand province, where U.S. Marines seized the Taliban stronghold of Marja.

Military officials describe the planned Kandahar offensive, expected to peak over the summer, as akin to tightening a noose on the city, the spiritual home of the Taliban movement. They say emphasis will be placed on controlling routes in and out of the city, and taking steps to restore people's confidence in the Afghan government.

At the same time, though, the Taliban and other militant factions have staged a concerted campaign of threats and assassinations against municipal and provincial officials, undermining the West's good-governance aims.

At tribal gatherings, known as shuras, that have taken place in or near Kandahar city in recent months, residents have told coalition commanders that they greatly fear for their own safety. They have also said they want Western forces to move in only if they intend to maintain a long-term presence and prevent insurgents from taking revenge on villagers and townspeople after the initial fighting dies down.